1. Field of Use
This invention relates to a method for spraying a processing liquid on the interior surface of green radial tires.
2. Description of the Prior Art
Various methods have been proposed for coating the inside of a tire with processing fluids both during manufacture and after manufacture. In some cases, the tire is "green" and in other cases it is cured. Concerning "green tires," one of the most important differences between a "green tire" and a finished tire is that the rubber of a "green tire" is still sticky, whereas the rubber of a finished tire has already been heated and cured and is no longer soft. Since the rubber of the "green tire" has not yet been hardened, the "green tire" can easily be damaged. The following patents illustrate the state of the art: U.S. Pat. Nos. 1,471,787; 2,407,806; 2,850,263; 3,346,412; 3,825,965 and U.S.S.R. Pat. No. 167,628. In U.S. Pat. No. 1,471,787, loosely journalled spreader rollers contacted the interior surface of the tire. Consequently, the rollers engaged the freshly sprayed interior and this resulted in irregularly thick layers of the spray liquid and also resulted in the formation of small, loose particles of the liquid which tend to stick to the interior surface of the tire.
U.S. Pat. No. 2,407,806 shows a mechanism with two railroad wheel-like discs to be inserted in the tire opening for contacting the two beads of the tire. The discs are then spread apart by means of a screw.
In U.S. Pat. No. 2,850,263, the tire spreader attachment was employed with finished tires and not green or unfinished tires, and that apparatus utilized a split ring for grasping and supporting the beaded edges of the tire. As a result, the entire interior of the tire, including the beaded edges, could not be thoroughly covered with the spray material.
In U.S. Pat. No. 3,346,412, there is described a method and apparatus for the spraying of the interior surface of a tire. However, this known method and apparatus is applicable only for conventional cylindrical green tires, that is for green tires which form a self-supporting (relatively rigid) cylinder, as can for instance be seen in FIG. 1 thereof. Such cylindrical green tires do not require a spreading to achieve accessibility of the interior of the tire. In the apparatus according to U.S. Pat. No. 3,346,412, the upper and lower edges of the tire are not grasped individually and moved away from each other. On the contrary, cylindrical green tires are clamped as a whole between upper and lower support plates which keep the green tire in position. These support plates do not have any gripping function at all in as far as the individual grasping of an edge of the tire is concerned, but are only brought in a line contact with the respective edge. This known apparatus and method is completely useless in as far as green tires with flexible sides (for instance radial tires) are concerned, since this known apparatus does not allow to grasp the edges of such a tire and to spread the flexible sides of the tire out. Therefore, this apparatus cannot be applied for spraying of the interior wall of a green tire having flexible sides.
In U.S. Pat. No. 3,825,965, an apparatus for cleaning the interior of tubeless tires is disclosed, in which apparatus the edges of the two side walls are set on two rotatable rims so that the tire is in a position as if it would be in its intended position on a vehicle wheel. After this positioning, the tire is then set under internal pressure as if it would be in use on a vehicle wheel. Once the tire is under pressure, a cleaning solvent is sprayed onto the interior wall of the tire by a nozzle which is arranged within the pressure chamber which is closed by the tire. Furthermore, the interior wall of the tire is brushed by a brush also arranged within the pressure chamber. Thus, this known apparatus is based on the pressurizing of the tire to bring it into a "blown-up" position and to spray the interior in this position, which principle differs completely from methods and apparatus by which the edges of a tire are clamped or gripped for holding the tire in a position for spraying and for manipulating the tire.
In USSR Author's Certificate No. 167,628 an apparatus for the spraying of the surfaces of a tire is described which shows an endless belt serving as a support on which the green tire rests in a horizontal position with its lower side wall contacting the endless belt, and which furthermore shows a gripping mechanism arranged above the tire which mechanism is apt to grip the upper edge of the upper side wall of the tire. By lifting the gripping mechanism it is intended to lift the upper side of the tire therewith and to spread the tire thereby. However, this will function only if the weight of the tire is large enough to keep the lower part of the tire resting on the transport belt while the upper side of the tire is lifted. Such a method may be applied with large and heavy tires of conventional construction. However, it does not function for modern radial tires. With radial tires, a spreading is possible only if both the upper edge and the lower edge of the tire are grasped individually and are then forced apart. Therefore, the apparatus known from the Russian Author's Certificate is applicable only for heavy conventional tires and is of no use for handling modern radial tires.